1. Field of the Invention
The present invention relates to an uninterruptible power supply system intended for sensitive equipment supplied from the public power distribution network and required to produce an equivalent voltage in the event of interruptions or disturbances to the public network.
It is aimed in particular at making it possible to power telecommunications equipment or computer equipment, or more generally any equipment for industrial use which accepts neither service interruptions nor brownouts.
2. Description of the Related Art
The equipment commonly encountered in the telecommunications sector is generally supplied with DC current at a voltage of 48 volts or with AC current at a voltage of 230 volts. This AC voltage originates from the local electricity distribution network which is generally backed up by a generating set, permanently, depending on the type of system powered.
Power supply chains conventionally comprise three different levels of conversion:
a primary level with a high voltage/low voltage transformation station, a generating set and a low-voltage distribution board;
a secondary level with rectifiers and accumulator batteries which constitute a 48-volt energy source;
a centralized tertiary level with power inverters which deliver an AC voltage of 230 volts.
The primary level is generally situated within technical premises (cellar, basement, ancillary premises) which are remote from the equipment rooms which comprise the secondary level and the tertiary level.
Accumulator batteries have been made reliable through the use of leakproof batteries and computer monitoring facilities which scan the failure modes.
The architecture of the present generation of power supply chains must evolve on account of the alterations encountered in the equipment:
the rising proportion of equipment exhibiting a 230 V/50 Hz power supply interface, to the detriment of the 48 V interface,
the considerable reduction in the power consumed by telecommunications equipment,
the ability of equipment to operate at extreme temperatures with no impact on their lifetime and on the quality of service.
These evolutionary factors lead to the favouring of second-generation power supply systems based on an architecture which includes Uninterruptible Power Supplies (UPS) to the detriment of 48 V sources and inverters.
French Patent 2 693 052 or the document CHIGOLET JC et Al. disclose power supply chains of the new generation whose operating principle exploits a technique of optimized and distributed energy. This technique makes it possible:
to separate the power supply and energy storage functions in the UPS of OFF LINE type so as to optimize the management of the batteries and thereby to increase their lifetime,
to improve the energy efficiency of the uninterruptible power supply chain as compared with the present-day technical solutions,
to relocate the AC distribution racks to the technical premises rather than in the equipment rooms, which will make it possible to eliminate operator constraints:
weight of the cabinet-mounted batteries, effects of high temperature on the lifetime of 5 the batteries when the production of cold is deliberately reduced so as to achieve energy savings,
risks of disturbances through electromagnetic radiation related to the closeness of the UPSs, maintaining of raised floors so as to conceal the large cross-section cables required for distribution at 48 V.
The British document GB-A-2 184 903 also discloses an installation which uninterruptibly supplies power to sensitive equipment exhibiting a current-supply interface. This installation comprises batteries and a fast switching device making it possible automatically to trigger a replacement source, the said replacement source ensuring that the charge of the said batteries is maintained by way of a rectifier.
The document EP 0 734 113 describes a system which exploits the inertia of the rotor, which continues to rotate even when the main power supply is cut, to trigger another generator which will cater for the electrical provision. Moreover, the presence is noted in this document of a Normal/Backup changeover switch (or LCIxe2x80x94Load Commutated Inverter) which switches over the networks, in the event of a failure.
These technical solutions of the new generation will enable the equipment to be powered at 230 V by UPSs which are located remotely in technical premises, with small cross-section distribution cables which can be trunked over decking or duckboards.
The drawbacks of the solutions known hitherto lie, on the one hand mainly in the recourse to backup sources which call upon generating sets, driven by diesel sets having non-negligible operational constraints:
environmental pollution (operating noise, vibrations, exhaust gases)
mediocre performance and dimensioning constraints,
high operational cost (preheating, servicing, etc.), and on the other hand in the use of a low-voltage board and of a Normal/Backup changeover switch (changeover switch and shunting device).
Moreover, the generating sets require a startup system dedicated to the replacement source (battery, rectifier, charger).
The present generation of solutions additionally requires ancillary backup devices for maintaining the connected equipment operational (backup for the air-conditioning, inverters protecting the computers against brownouts and disturbances, etc.)
The present invention aims to alleviate these drawbacks by proposing an Uninterruptible Power Supply system which does not include any function of Normal/Backup swapover between the local electrical network and the replacement source, this replacement source moreover being environmentally friendly.
To this end, system which uninterruptibly supplies power to sensitive equipment exhibiting an AC current supply interface, is characterized in that it comprises downstream of a high/low voltage transformation station, a direct link to at least one uninterruptible power supply (UPS) unit which comprises batteries in parallel and a fast switching device, making it possible automatically to ensure the triggering or the starting up of a replacement source (RS) in the event of a failure of the local electricity network, the said replacement source being coupled to the said batteries of the (UPS) and delivering a DC current required for maintaining the charge of the said batteries, thereby making it possible to dispense with the Normal/Backup changeover switch of the low-voltage distribution situated upstream of the (UPS).